ACERTMGR

This is an automated certificate manager using ACME/letsencrypt.

Running ACERTMGR

The main file acertmgr.py is intended to be run regularly (e.g. as daily cron job) as root.

Requirements

• Python (2.7+ and 3.3+ should work)
• python-dateutil
• PyYAML
• pyOpenSSL

Initial Setup

First, you need to provide two key files for the ACME protocol:

• The account key is expected at /etc/acme/account.key
• The domain key is expected at /etc/acme/server.key (note: only one domain key is required for all domains used in the same instance of acertmgr) If you are missing these keys, you can create them using openssl genrsa 4096 > /etc/acme/account.key and openssl genrsa 4096 > /etc/acme/server.key respectively.
• Do not forget to set proper permissions of the keys using chmod 0400 /etc/acme/*.key

Secondly, you should download the letsencrypt CA certificate:

• wget -O /etc/acme/lets-encrypt-x3-cross-signed.pem https://letsencrypt.org/certs/lets-encrypt-x3-cross-signed.pem
• The path to this file must be entered in the configuration, see below.

Thirdly, you should decide which challenge mode you want to use with acertmgr

• webdir: In this mode, challenges are put into a directory, and served by an existing webserver. Make sure the target directory exists!
• standalone: In this mode, challenges are completed by acertmgr directly. This starts a webserver to solve the challenges, which can be used standalone or together with an existing webserver that forwards request to a specified local port.

Finally, you need to setup the configuration files, as shown in the next section. While testing, you can use the acme-staging authority instead, so you avoid issuing too many certificates.

Configuration

The main configuration is read from /etc/acme/acme.conf, domains for which certificates should be obtained/renewed should be configured in /etc/acme/domains.d/{fqdn}.conf.

All configuration files use yaml syntax.

• Example global configuration file:

---

mode: webdir
#mode: standalone
#port: 13135
account_key: "/etc/acme/account.key"
server_key: "/etc/acme/server.key"
webdir: /var/www/acme-challenge/
authority: "https://acme-v01.api.letsencrypt.org"
#authority: "https://acme-staging.api.letsencrypt.org"

defaults:
  cafile: /etc/acme/lets-encrypt-x3-cross-signed.pem

• Example domain configuration file:

---

mail.example.com:
- path: /etc/postfix/ssl/mail.key
  user: postfix
  group: postfix
  perm: '400'
  format: key
  action: '/etc/init.d/postfix reload'
- path: /etc/postfix/ssl/mail.crt
  user: postfix
  group: postfix
  perm: '400'
  format: crt
  action: '/etc/init.d/postfix reload'
- path: /etc/dovecot/ssl/mail.crt
  user: dovecot
  group: dovecot
  perm: '400'
  action: '/etc/init.d/dovecot reload'

jabber.example.com:
- path: /etc/ejabberd/server.pem
  user: jabber
  group: jabber
  perm: '400'
  format: key,crt,ca
  action: '/etc/init.d/ejabberd restart'

www.example.com example.com:
- path: /var/www/ssl/cert.pem
  user: apache
  group: apache
  perm: '400'
  action: '/etc/init.d/apache2 reload'
  format: crt,ca
- path: /var/www/ssl/key.pem
  user: apache
  group: apache
  perm: '400'
  action: '/etc/init.d/apache2 reload'
  format: key

Security

Please keep the following in mind when using this software:

• DO read the source code, since it is intended to be run as root
• Make sure that your configuration files are NOT writable by other users - arbitrary commands can be executed after updating certificates